The present invention relates, in general, to a numerical control apparatus and more particularly to a coordinate system display guide of the numerical control apparatus for displaying relative movements between different programmed virtual coordinate systems and tool paths.
A numerical control apparatus controls the positioning of a tool relative to a workpiece using numerical values to cut or machine the workpiece, even when the workpiece is of complex shape.
A conventional numerical control apparatus will be described with reference to FIGS. 10-12.
FIG. 10(a) shows a machine coordinate system 11, which represents a specific machine position, a workpiece coordinate system 12, which represents the coordinate system of a workpiece, and a virtual (local) coordinate system 13, which designates a coordinate system relative to the workpiece coordinate system 12. The cutting program of the numerical control apparatus, which defines the cutting or machining operation of a workpiece, is written with respect to the workpiece coordinate system 12. The virtual coordinate system 13 may be set (relative to the workpiece coordinate system 12) to enable the easier design of a cutting or partial-cutting program.
FIG. 10(b) shows translation parameters X, Y, and Z, which represent a position in a virtual coordinate system relative to the workpiece coordinate system 12, rotary axis command parameters I, J, and K corresponding to the translation parameters X, Y, and Z, respectively, and a rotary angle parameter R. By programming a shape in the workpiece coordinate system X, Y, registering the shape as a submodule, setting a virtual coordinate system 13, and then executing the shape submodule, the shape will be created relative to a specified optional plane. FIG. 10(b) further illustrates motions x, y, and z and the rotation of the rotary angle R relative to the Z axis (K).
FIG. 11 illustrates a graphic display device of a numerical control apparatus, which displays a tool path 26 defined by a cutting program for a set virtual coordinate system 13 and a cube 10 which serves as a visual reference point. The graphic display device also includes a menu frame 15, a screen frame 16, a display frame 17, and a tool path drawing menu 25. In FIG. 11, regardless of the virtual coordinate system 13 currently set only the tool path 26 that has already been converted with respect to the set virtual coordinate system 13 is displayed. That is, in conventional numerical control apparatus, only the tool path 26 that has been converted with respect to the set virtual coordinate system 13 is displayed. Although the program designer may attempt to check the virtual coordinate system 13 in the cutting program by variously changing the visual reference point, the designer cannot determine whether the virtual coordinate system 13 is being set as intended. This is a problem with the conventional numerical control apparatus.
In FIG. 12, a tool path 26A is displayed when a virtual coordinate system 13 is set a predetermined linear distance, defined by the X, Y, Z parameters, relative to the workpiece coordinate system 12. FIG. 12 also shows a second tool path 26B relative to a second virtual coordinate system 13', which is rotated about the X axis of the virtual coordinate system 13 of the tool path 26A. The tool paths 26A and 26B are shown from within the same visual field. However, the set virtual coordinate system 13 or 13' is not displayed so that the program designer cannot determine whether the desired virtual coordinate system has been set. This too is a problem.
Although objects depicted by solid lines and broken lines are shown in FIG. 12, only objects designated by solid lines are actually displayed on the graphic display device. Similarly, in FIG. 12, both tool paths 26A and 26B are shown together to facilitate a better understanding of the present invention, but in practice only one of the tool paths 26A and 26B are displayed.